The present invention relates generally to incinerator systems for the abatement of process emissions and more particularly, to a novel filter for a regenerative incinerator used in oxidizing contaminants from process emissions.
Process emissions often contain combustible contaminants that, if released to the atmosphere, have the potential of polluting the environment. However, the amount of combustible material contained in such emissions is generally below several thousand ppm and, accordingly, will not ignite or propagate a flame at ambient temperature.
Incinerators increase the temperature of such process emissions to a level above the ignition temperature of the combustible contaminants by the use of heat derived from a supplemental energy source, therefore allowing for oxidation of the emissions. Regenerative incinerators recover heat remaining in the cleansed exhaust gas to increase the temperature of emissions entering the incinerator thereby minimizing the amount of supplemental energy required to raise the emission to its ignition temperature.
Known regenerative incinerators typically comprise a plurality of conventional regenerator beds that communicate with a combustion chamber. The regenerator beds contain conventional ceramic heat exchange elements. Admission of emissions into each regenerator bed is controlled by a valve network. During operation of a regenerative incinerator that contains, for example, three regenerator beds, emissions pass through a first regenerator bed to pick up heat therefrom, thence to the combustion chamber for oxidation. Following oxidation to CO.sub.2 and H.sub.2 O, the cleansed air then passes through a second regenerator bed, which is operating in the regenerative, or heat receptive, mode for discharge to atmosphere or to a purified air duct which conducts purified air to a third regenerator bed to purge the bed of contaminants. Thus, each regenerator bed performs three modes of operation: a feed mode, a heat receptive mode, and a purge mode.
The process emissions that require abatement control devices, such as found in the wood industry, or in coating, laminating, painting, or dry cleaning processes, often create difficulty because of a suspended particulate in the exhaust air which feeds the regenerative incinerator. Thus, one problem that materially effects the efficiency of such incinerators is fouling and plugging of regenerator beds because of the presence of this particulate. Moreover, often these particulates typically contain inorganic material, creating undesirable solid particles of noncombustible ash, known as fly ash, when burned.
Accumulation of the particulate material, such as under a regenerator bed in a regenerative incinerator, will plug the bed thereby preventing or severely reducing the flow of the process emissions or cleansed air, depending upon the mode of operation for the regenerator bed. Attempts to burn or "bake" off the particulate material are inadequate because residual fly ash generally collects in the mid-bed regions, which are higher than the typical fouling segments. This phenomenon creates great difficulties and thus regenerative incinerators become too inefficient for process emissions that contain these particulates.